Tax-free municipal money market fund assets declined by $2.25 billion to $316.80 billion in the week ending April 11, representing a major acceleration of outflows from the previous week, according to the Money Fund Report, a service of iMoneyNet.com.

The outflows far eclipsed the $252.5 million that investors withdrew from tax-exempt money funds in the week ending April 4, when they finished with $319.05 billion.

The average seven-day simple yield for the 478 tax-exempt money funds in the report decreased to 0.02%, while the average maturity remained at 27 days.

The assets of the 1,139 taxable money funds grew $19 billion to $2.411 trillion in the week ended April 12, compared with outflows of $4.23 billion and total net assets of $2.392 trillion for the week ended April 5.

The average seven-day simple yield for all taxable money funds remained at 0.02% for the second consecutive week, while the average maturity was unchanged at 45 days.

Overall, the combined assets of the 1,617 money funds raked in $16.75 billion and finished with total net assets of $2.728 trillion for the week ended April 12. That compares to $2.711 trillion in total net assets for the week ended April 5, when they suffered outflows of $4.49 billion.